The present invention generally relates to telecommunications and, more particularly, to methods and devices for allocating data in a wireless communication system.
In telecommunications systems, channel estimation may be performed for coherent detection to compensate for distortion or errors introduced due to channel fading. One technique for estimating a channel may include the use of pilot signals or pilot symbols. A transmitter or transmitting side may send pilot signals to a receiver or receiving side through predetermined sub-carriers. The receiver may be programmed with the pilot signals so that the pilot signals sent from the transmitter are “known” to the receiver. Upon receiving the pilot signals, the receiver may estimate the channel by comparing the transmission the receiver actually receives with the known symbols that the receiver ideally should have received. Pilot signals may be continually transmitted from a transmitter to a receiver because the channel may be constantly changing. Furthermore, pilot signals may be transmitted across a wide range of frequencies or sub-carriers because the channel may vary with frequency.
The use of pilot signals may be a trade-off between accurate channel estimation and data bandwidth. Specifically, when more pilot signals are used, more accurate channel estimation may be achieved and, however, more sub-carriers may be used to transmit the pilot signals rather than data. On the contrary, when less pilot signals are used, more sub-carriers may be used to transmit data and, however, a higher frame error rate may result. Therefore, it may be desirable to have methods and devices that are able to enable accurate channel estimation without adversely affecting the entire throughput. Furthermore, the characteristics of a channel may change as the relative speed between a transmitter and a receiver changes. Therefore, it may also be desirable to have methods and devices that are able to allocate pilot signals based on the relative speed between the transmitter and the receiver.